Molded conductor.



E. G. (1115011.. MOLDED CONDUCTOR. APPLIGATIOH FILED HAD. 7, 1910.

11,003,535, Patented Nov. 14, 1911.

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UNITED STATES PATENT OFFICE.

EMERY G. GILSON. 0F SCHENECTADY, NEW YORK. ASSIGNO'R TO EENERAL ELECTRIC COMPANY. A CORPORATION OF NEW YORK.

MOLDED CONDUCTOR.

Speeifieatiun of Letters Patent.

Pat-e111 ed Nov. 14, 1911.

Application filed March 7, 1910. Serial No. 5467,73 9.

To all whom it may concern:

Be it known that l, Ennur (1. (iILSON, a citizen of the United States, residing at Schenectady, in the county of Schenectady. State of New York, have invented certain new and useful llllPl'OVGIllOlliS in Molded Conductors, of which the following is a specification.

My invention relates to the production of molded articlesemployed as eurrent-earrying conductors, particularly current collectors for dynainn-electric machines.

lllodern electrical practice requires for certain kinds of service a collector or brush having a high conductivity and a low eontaet resistance. \Vhen the brush is to be used with a con'nnntating machine it is desirable that the transverse resistance of the brush shall be relatively high, to reduce sparking by cutting down the current in the short-vireoited coil, as is well innlerstood. These. apparently antagonistic properties are nesent in a brush made according to my invention. The brushes consist of graphite assmriated with a metal of the iron group. The metal constituent is preferably introduced by mixing it in the form of an oXid with finely divided graphite, the mixturethen being fired at a. relatively high temperature. The product is finally molded by the application of pressure. no .binder being required; the material itself having the prop(.-rt. o't' molding under pressure.

molded a rticle made in accordance with myiurention is shown in the accompan \-'ing drawing.

lu carrying out my process any pure form ol graphite may be employed: but I find that the best results are. obtained when using graphite which has been subjected to the following treatment: 100 parts oi finely dirided graphite. preferably eylon graphite. are mixed-with about parts of potassium carbonate, also in a finely divided state. The mixture is placed in.a graphite crucible and fired in a suitable furnace to a temperature of about 900 A gas fired furnace. or an electrical resistance furnace can be used. The firing is continued for abo it four hours when working with a. mass 0 about 500 grams. After cooling. the mixture is washed with water until the graphite has been entirely freed from potassium carbo mate, as can be easily determined by testing a con'ipound analogous thereto.

produced when pressing.

purilies from the grapl'ite and also changes it in some way so as ti make it finer and more easily compacted. 100 parts of graph- 6" ite, preferably that prl pared as above described, are now mixed, with 50 parts of iron oxid in powdered form. I prefer to use the red oxid, Ie. but other oxids. such as the black oxid. Fed) can likewise be used. In the place if ,i'ron oxid. nickel oxid, or. in general. a m tal oxid of. the iron group can be used. but :s' iron is eheap and gives good results it is 1: referably employed. The above proportions (fgraphite and oxid are given as a matter of illustration and need not. be strictly achered to, the parti(ailar-mixture depending somewhat upon the noperties desired in the completed brush. A higher pereintage of iron decreasesthe conductivity. but increases the strength of the brush somewhat. This mixture is fired in a graphit: crucible to a temperatnre of about 900 (l. in a suitable furnace. The firing treatnn nt reducesthe iron oxid to metallic iron. \ihich in turn combines with the graphite t) form a earbid, or I do not wish, however. to be lii lited by this view as to what takes place during the firing treatment. as the iron aid the graphite are so thoroughly mixed that it is ditlicult to say in what form the irm is present after the mixture has been fi-re 1. After firing the mixtureis compacted iito predetermined form by the application of a pressure of about 20 tons to the square inch. or even more. The finished brusl es arestrong, considerably harder than g'aphite, and more conductive than a carbon brush.

The electrical resistanze of the. molded article is greater in the lirection in which the pressure was a plied when molding the same than in a (lireetioi at right a les thereto. On the average the ratio oflreslstanee is seven or ten to 01 e. r The, difference in resistance is due to a la ininated structure, This propertv is utilized by pressin the brush in sue a manner that the highest; resistance in the 106 brush when applied to a commutatin ma-t chine is across the short-uircuited coi and will thus reduce the curre 1t.

What I claim as new and desire to secure by Letters Patent of the United States, is- 1. The process, which consists in mixing graphite and an oxid of a metal of the iron group, both in powdered form, firing said mixture to a temperature of about 9005 (1., and then molding the product by the application of pressure.

2. The process, which consists in mixing graphite and oxid of a metal of the iron group, both being finely divided, firing said mixture, and pressing into predetermined form.

3. The process, which consists in mixing finely divided graphite and finely divided iron oxid, firing said mixture to a temperature of about 900 (1., and finallymolding' said mixture by the application of pressure.

4. As an article of manufacture, a molded mass oi carbon containing iron combined with carbon uniformly distributed there= through.

5. A molded electrical conductor, consisting of graphite associated with an ironcarbon compound.

7. The process, which consists in firing Ceylon graphite 1n the presence of a potassium compound, subsequently removing the potassium compound, mixing with the graphite and oxid of iron, firin said mixture at about 900 0., and fina 1y pressing the productinto predetermined form.

8. As anarticle of manufacturefa molded mass consistingvsubstant-ially of iron and graphite, the latter element preponderating in amount. 1

In witness whereof, have hereunto set V my hand this 4th day of March, 1910.

EMERY G. GILSON.

Witnesses BENJAMIN .HULL, HEInN ()RFORD.

Copies of this patent may be obtained tor-five cents each, by addressing the Commissioner of Patents,

' Washington, D. G. 

